1. Field of the Invention
The present invention relates to a method of measuring the length of an elongated, flexible element such as a rope, line or cable and a device for measuring and communicating the measured length or information determined from such measurement about a rope or other elongated, flexible element passing through the device.
2. State of the Art
Pulleys are used for various applications in many different activities. Pulleys may be used with outdoor recreational activities, such as rock climbing, mountaineering, sailing, caving, and mountain rescue work. However, pulleys are also employed in other applications, such as in rescue work in urban and industrial settings, in safety restraints in urban and industrial settings, in law enforcement work, in tree climbing, and in military applications, among many other applications. The foregoing activities will be referred to herein individually and collectively as “climbing applications.”
Generally, a pulley has a frame and a sheave or wheel that rotates on a bearing carried on an axle or pin. A pulley used for hauling a load or rescue conventionally includes an attachment point for a carabiner, facilitating maneuvers and temporary installation. Conventionally, both static ropes and dynamic ropes are used in conjunction with pulleys in climbing applications. Static ropes or “Low Stretch” ropes conventionally stretch less than 4 percent when loaded with a 200 pound load and many will stretch less than 2 percent at this load. Dynamic ropes are designed to stretch and absorb a portion of the impact force in a fall.
The ropes, both static and dynamic, used in climbing applications, conventionally do not include markings for incremental measurement of the rope length. Ropes having a middle marker are available. For example, Sterling Rope Company, Inc. of Scarborough, Me. offers a bi-color rope, changing the color of the rope at the center to aid in finding the middle of the rope, which may be critical in rappelling, or descending, applications.
Knowing the length of a portion of a rope being employed in an indoor or outdoor rock climbing situation, a search and rescue operation, industrial rescue operation, or other situation may be useful. The length of a given rope portion may be used to determine the length of the remaining portion of a rope of a standard or known length, or to determine the distance an object attached to the rope has traveled. For example, in a rescue situation, a rescuer may be lowered down a cliff to a victim, and knowing the distance to the victim may be useful for other rescue team members. In a rock climbing situation, it may be useful for a climber ascending a cliff to know the distance ascended, in order to determine if the same rope, doubled over, may be used to descend, or “rappel,” the cliff. Alternatively, it may be useful for a climbing partner on the ground, managing the ropes, or “belaying” to determine if the same rope may be used to lower the climber from his or her high point to the ground, on the same rope. Many climbers have been injured after being lowered off the end of a rope, then plummeting to the ground below.
In view of the foregoing, it appears that a portable device for determining the length of a rope or a portion of a rope would be useful.